ATI drivers were a horror show for the longest time on windows never mind linux. What Nvidia did was have have basically the same driver code for all operating systems with a compatibility shim. If you were using any sort of professioinal 3d software over the previous 2 decades Nvidia were the only viable solution.
Source: Was burned by ATI, Matrox, 3dlabs before finallly coughing up the cash for Nvidia.